Study of the Impact of Nano-particles on strength development of cemented paste backfill

ABSTRACT: This paper evaluates how adding various types of nanoparticles (NP) affects one of the key engineering parameters of cemented paste backfill (CPB), which is strength development as a function of curing time. To achieve this objective, varying doses of four distinct kinds of NPs, including nano-silica (SiO2), nano-calcium carbonate (CaCO3), nano-iron oxide (Fe2O3), and nano-aluminum oxide (Al2O3), were utilized. To avoid NP agglomeration in the CPB microstructure, which could have a detrimental impact on the CPB's mechanical performance, an ether-based Polycarboxylate Superplasticizer (SP) was used to evenly disperse the NPs throughout the hydration reaction medium. Type I ordinary Portland cement was used to prepare CPB and tap water was also utilized to blend the CPB components. A comprehensive testing and monitoring programme was developed to evaluate the effect of NPs on the development of the strength of CPB. Uniaxial compressive test (UCS) was done to measure the sample's strength over curing time. Nano-CPB samples or cement pastes were subjected to several microstructural analyses or tests, including thermal analysis (thermogravimetry (TG), differential thermogravimetry (DTG)), mercury intrusion porosimetry (MIP) tests, and X-ray diffraction (XRD) analysis to gain insight into the fundamental mechanisms responsible for the behaviour observed. In the absence of the dispersing agent, the aggregated NPs were found to degrade the strength development of nano-CPB samples. In contrast to the control sample, nano-CPB samples combined with a dosage of SP exhibited greater UCS values. Microstructural analysis results indicated that the addition of NPs increased the generation of hydration products, which primarily increased the resistance to shear stress between tailings particles. The highest overall improvement in nano CPB's strength was reported in samples containing a fixed concentration of SP (0.125%) and NPs (1%).